In modern society, chlorofluorocarbons are widely used in chemical, electronic and appliance industries as solvents, cleaning agents, refrigerants, blowing agents for solid foams and the like. These chlorofluorocarbons are most often made by processes which utilize antimony halide catalysts. Typically the reactions to produce these chlorofluorocarbons are between chlorinated hydrocarbons and hydrogen fluoride in the presence of these antimony halide catalysts.
As is the case with any catalytic process, in time the catalytic activity is reduced to such a level that the process becomes uneconomical. The spent catalyst must then be removed from the reaction vessel and replaced with fresh catalyst.
Typically, spent antimony halide catalysts comprise antimony pentachloride, antimony trichloride, antimony trifluoride, various antimony chlorofluorides, arsenic chloride, arsenic fluorides, iron chloride, hydrogen fluoride, hydrogen chloride, chlorinated hydrocarbons and chlorofluorinated hydrocarbons. Because of the very toxic and corrosive nature of the spent antimony halide catalysts, great care must be taken in handling them, either to recover the catalyst by regeneration or to treat them for safe disposal. Thus, any treatment of the spent antimony halide catalysts must be in a carefully controlled environment wherein any acidic and/or toxic substance released must be captured and rendered safe to handle. If a desired treatment of the spent catalyst is hydrolysis to render the antimony and arsenic halides more amenable to handling safely, such hydrolysis must be carried out with minimal corrosion of any vessel.
In the normal operation in the manufacturing processes for chlorofluorocarbons using antimony halide catalysts, particularly in any large scale manufacturing, these spent catalysts are removed from reaction vessels and stored in containers such as railroad tank cars or tank trucks which can be used to transport the spent catalysts to a separate location for recovery of the catalyst values or treatment for disposal. Storage of spent catalysts until sufficient quantities are accumulated for transport to the recovery or disposal area results in precipitation and settling of a portion of the spent catalysts, making it very difficult to extract them out from the storage vessels. The hazardous nature of the spent catalysts precludes removing the catalysts manually from the containers.
This handling of partially solidified spent catalysts in storage tanks and in particular the extraction of the spent catalysts from the storage tanks into suitable equipment for the regeneration or for treatment for proper disposal has been a problem for some time.
It is therefore an object of the present invention to provide means to facilitate removal of spent antimony halide catalysts from storage tanks. It is a further object of the present invention to provide improvement in a process for recovery or disposal of spent antimony halide catalysts by providing a means to facilitate transfer of spent antimony halide catalysts from storage tanks to processing equipment for said recovery or disposal.